Vascular access devices are widely used to deliver a wide variety of substances, including fluids, medications including chemotherapy, blood products and total parental nutrients. Transcutaneous vascular access devices include standard central venous catheters (CVC), tunneled central venous catheters and peripherally inserted central venous catheters (PICC). These catheters pass through the skin, enter a vein and terminate in a central venous location. They can have one or more lumens and corresponding hubs. Transcutaneous VADs can be left at the insertion site for weeks or more, and as such require regular flushes with saline or an anti-coagulant solution to protect against thrombus formation and occlusion. Other types of VADs such as totally implantable VADs are used in patients who require access for weeks to months. The implantable VADs typically have a metal or plastic port that is implanted into the subcutaneous tissue and anchored to the fascial tissue along with a catheter portion that enters a vein. The implantable VADs also require regular flushes with anti-coagulant solution, typically concentrated heparin to prevent thrombus formation and occlusion.
Currently available VADs bear significant risk (about 10%) of introducing infection to a blood stream, which can lead to serious costly complications such as bacteremia, sepsis or even death. Furthermore, because they are in constant contact with the blood stream, the VADs require regular flushes to clear stagnant blood and prevent thrombus formation and occlusion. Even with regular flushes occlusions occur in approximately 30% of patients, requiring treatment with thrombolytic agents or device removal and reinsertion of a new device, which are costly, can interfere with patient care and result in complications. In addition, most VADs require radiologic (chest radiograph or fluoroscopy) confirmation of proper positioning in a central venous location and must be carefully handled by trained clinicians. A trained clinician is required because the introduction of an even modest amount of air into the device can lead to catastrophic air embolism, which can be fatal. Still furthermore, VADs must generally terminate in, or at least in the vicinity of, the right atrium. Repeated instrumentation in chronically ill patients, such as hemodialysis patients, can lead to venous fibrosis, stenosis and occlusion, which can lead to significant morbidity and can be a formidable challenge in patients who still require vascular access.
Accordingly, there is a need for vascular access devices that are easy to implant and access, for delivering medicine and fluids to patients, which are less prone to occlusion and the various limitations outlined above.